1. Preheat the oven to 350oF; place the rack in the center of the oven.

2. Place the bread pieces in a large bowl. Add the milk and cream, and stir well to soak all pieces. Set aside.

3. In a medium bowl, beat the eggs and sugar until thick and creamy, and lightened in color. Add the melted butter, vanilla seeds, cinnamon, and nutmeg. Pour this mixture over the milk-soaked bread. Gently fold in the optional raisins.

4. Pour the mixture in a casserole set in a shallow roasting pan and prepare a water bath: pour enough boiling water in the roasting pan to reach half-way up the sides of the casserole.

5. Bake until set and golden brown, about 45 minutes.

6. Meanwhile, prepare the vanilla sauce. In a small, heavy saucepan, heat cream, vanilla beans, and vanilla pod until it is almost boiling, with bubbles forming at edges. Discard the vanilla pod. Quickly whisk together egg yolks and sugar until thick, creamy, and lightened in color. Slowly pour 1/3 of hot cream into the egg/sugar mixture, whisking constantly. Gradually add the egg/sugar mixture to the saucepan with the remaining cream, whisking constantly. Continue to cook, stirring constantly, until the mixture thickens enough to coat the back of a spoon. Remove from the heat immediately and strain if necessary. Set aside.

7. Remove the bread pudding from the roasting pan. Serve warm with warm sauce, or cold with chilled sauce.